Prior art of possible relevance includes the following U.S. Pat. No. 1,969,710 issued Aug. 7, 1934 to Jones; U.S. Pat. No. 1,994,103 issued Mar. 12, 1935 to Huey; U.S. Pat. No. 2,119,439 issued May 31, 1938 to Parmellee; U.S. Pat. No. 2,365,779 issued Dec. 26, 1944 to Schwab; U.S. Pat. No. 2,423,272 issued July 1, 1947 to Thornton; U.S. Pat. No. 2,485,117 issued Oct. 18, 1949 to Settle; U.S. Pat. No. 2,592,805 issued Apr. 15, 1952 to Hutchinson; U.S. Pat. No. 2,687,523 issued Aug. 31, 1954 to Bernhardt; U.S. Pat. No. 3,945,044 issued Mar. 23, 1976 to McGee et al; and U.S. Pat. No. 4,215,436 issued Aug. 5, 1980 to Ketterer.
The above identified prior art illustrates, in a variety of environments, the need for providing protection for the lens of a viewing device of the sort generally intended to protect the eyes of a wearer of the viewing device during some sort of endeavor. In such devices, the primary protection for the eyes is provided by the lens of the viewing device itself. There is also recognized the fact that the wearer of the viewing device cannot be fully protected in his endeavor or, in some cases, the lens of the viewing device cannot be so protected during performance of an endeavor where the lens is permitted to become obscured. Such obscuration interferes with the vision of the user and decreased visual acuity may lead to the creation of a hazardous situation. Alternatively, obscuration of the lens may be such as to reduce the vision of the user causing a commensurate reduction in the efficiency of the task being performed by the user while wearing the viewing device.
Consequently, the exemplary prior art listed above suggests the use of transparent covers for the lens of the viewing device, which transparent cover protects the lens from obscuration and which can be removed or changed periodically when it becomes sufficiently obstructed asto interfere with the wearer's vision.
A principal defect of virtually all of the prior art structures listed above resides in the fact that the transparent lens cover employed cannot be readily changed when obscured during the performance of a task by the wearer of the viewing device without a substantial interruption in the performance of that task. This, of course, decreases the efficiency of the user in performing his task and, in some cases, where the task is such as to require acute attention to rapidly happening occurrences, can lead to the creation of a hazardous situation.
An exception to the foregoing is found in the structure disclosed in McGee et al U.S. Pat. No. 3,945,044 which relates to a goggle provided with a plurality of lenses. The lenses are superposed over one another and provided with nonaligned tabs. When the outermost lens becomes obscured, the user may, with one hand, grab the tab associated with that lens and quickly remove it from the goggle, leaving the other hand free to continue performing the task at hand. This sequence of events may be performed serially as each successive lens becomes obscured.
While the approach exemplified by the McGee patent has been successful, the drawbacks include the fact that the protective covering for each lens is another lens with the consequence that the structure is less economical than a transparent film, and the tear off lenses must be discarded by the user without creating a hazard. Another drawback resides in the fact that there is a limited number of lenses that can be carried by the goggle of McGee et al at a given time such that during the performance of a task of substantial duration, it is conceivable that all of the lenses may become obscured before the task is completed.
Furthermore, many of the prior art structures cannot be used without difficulty in all environments. For example, many of the prior art structures identified above employ films which overlie a lens or the like. When working in an environment wherein liquid droplets are present, droplets may find their way to an edge of the protective film. Because the protective film is in contact with or very close to the lens, surface tension of the liquid droplet may cause the liquid to flow between the protective film and the lens thereby distorting the vision of the user where the liquid is transparent or obscuring the vision of the user where the liquid is opague as, for example, a paint.
The present invention is directed to overcoming one or more of the above problems.